Dopaminergic D4 receptor polymorphism among 24 populations of India: an anthropological insight

Various studies have tried to elucidate the genomics underlying the ethnic diversity of Indian populations. The 48-basepair variable number tandem repeat (VNTR) of the DRD4 gene, besides its clinical importance, has been a subject of interest for understanding human evolutionary history worldwide. In spite of its highly polymorphic nature it has not been much explored by anthropologists, especially in the Indian context. In the present study, an attempt was made to infer the allelic variation of the repeat allele among 24 Indian ethnic groups belonging to different ethnic and linguistic groups along with different geographic affiliations. Only the 2R, 3R, 4R, 5R, 6R, and 7R repeat alleles were found in the studied populations, with 4R being the most frequent followed by 2R. All the other repeat alleles (3R, 5R, 6R, and 7R) occurred at very low frequency. Based on the 4R and 5R frequencies, the study reveals a common genetic substratum of the Indian population as already proposed by earlier studies. Further, the study also highlights the inflow of genes from the north.